Certain types of polymers exhibit film-forming properties and when dissolved in an organic solvent, can be applied for the purpose of providing a water-resistant coating on a substrate. Usually, the film-forming polymer in the solvent is applied to the particular substrate to be coated, and the solvent is allowed to evaporate or removed leaving a film of the polymer.
Generally, however, such water-resistant, film-forming polymers are soluble only in organic solvents, i.e., they are substantially insoluble in water. The use of such organic solvents generally is undesirable since they exhibit environmentally adverse properties, are often hazardous or flammable, and are generally expensive. In order to avoid the environmentally adverse effects of such organic solvents as well as to reduce the cost involved with using such solvents, rather complicated solvent recovery procedures must be used.
Typical of such polymers are copolymers of N-vinylpyrrolidone with .alpha.-olefins, vinyl acetate, styrene, acrylates, acrylic acids, amides, maleic acid, mono and diesters of maleic acids, and the like.
In parent application Ser. No. 07/975,811, a method is disclosed for providing a stable microemulsion of a particular class of water-insoluble film-forming polymers in water. The microemulsions thus formed, can be utilized to produce films of the particular film-forming polymer on a given substrate. For example, the microemulsion can be used as a coating for substrates, such as, wood, metal, glass, and the like. In addition, various active ingredients, e.g., fungicides, preservatives, insecticides, insect repellents, pheromones, radiation absorbents, dyes, and the like, can be included in the composition.
The compositions disclosed therein are composed of the water-insoluble polymer, a surfactant, and a long-chain alkylpyrrolidone. The amounts of the polymer surfactant and long-chain alkylpyrrolidone can vary within a broad range. However, the relative compositional ranges of each must be such that a clear, stable microemulsion or solution of the insoluble polymer is obtained on the addition of water.
A significant problem in the use of agriculturally active chemicals is that since they are applied to soil and plant surfaces, they are susceptible to being washed off by rain and/or water spray used for irrigation. This adversely affects the efficiency of the chemicals, since the longer the chemical remains in contact with the plant or soil surface, the more effective it is.